Pneumatic hammer.



G. D. ROBERTS.

PNEUMATIC HAMMER.

APPLICATION TILED JULY 25, 1911.

Patented Sept. 3, 1912.

1 At fomey lllll WITNESSES UNITED STATES PATENT OFFICE.

GRIFFITH D. ROBERTS, 0F COLUMBUS, WISCONSIN.

PNEUMATIC HAMMER.

To all whom it may concern:

Be it known that I, GRIFFITH D. ROBERTS, a citizen of the United States, residing at Columbus, in the county of Columbia and State of WVisconsin, have invented a new and useful Improvement in Pneumatic Hammers, of which the following is a specification.

My invention relates to a class of pneumatic hammers, propelled by power and used for forging metals and the object of my invention is to provide a means for raising the hammer to the top of its stroke preparatory to starting on a new piece of work.

My invention relates more particularly to a pneumatic hammer invented and patented by me in Patent Number 989051.

In the accompanying drawings wherein like reference characters refer to corresponding parts throughout the several viewsFigures 1 and 2 illustrate my invention as viewed from opposite sides. Fig. 3 is a front view of my invention.

A represents the frame of the hammer to which is attached the belt pulley B, the crank shaft G and the pitman D, carrying the upper piston rod E. To the frame A is also attached the air cylinder F in which are the upper or power piston E attached to piston rod V and the lower or hammer piston V attached to piston rod V. Between the two pistons is located the reciprocating air controlling valve G, provided with an opening to the air at 9 Fig. 1. A spring, R, holds the valve stem G in outermost position as shown in Figs. 1 and 2. In this position the valve G is open. The lever H has a movable bearing Ii and has attached to its lower end a pawl L engaging in corrugations on the hammer T. The lever II has intermediate its ends aslanting slot K that permits a rocking motion of the upper end, when the bearing K is lowered a little but when lowered farther the upper end resting on the valve stem G permits the withdrawal of the pawl Q.

The slide I engages the outer end of pawl L at its lower end and at its upper end is wedge shaped, Fig. 2, so that as it descends it closes the air valve. The slide I is also wedge shaped near the lower end, Fig. 2, to gradually withdraw pawl L when depressed.

The pawls L and Q, are pressed toward Specification of Letters Patent.

Application filed. July 25, 1911.

Patented Sept. 3, 1912.

Serial No. 640,506.

the hammer rod by springs S S, Figs. 1 and 2. The pawl L, Fig. 2, is made strong and the ratchet teeth on the hammer rod T are made coarse to resist the downward pressure of the hammer rod when engaged and the upper piston working. The pawl Q has its end rounded to engage with corrugations on the hammer rod in any posit-ion whether the pawl L is engaged or not when the pressure on the hammer is light.

The slides H and I are carried up and down by the arms M M sliding in lugs N N on the frame. The arms'M M are held up by springs O O and are pulled down by rods P P connected with a pedal W at the base of the frame.

It is operated as follows: Pressure on the foot lever pulls downward the arms M M and the slide I acts to close the air valve G. The upper reciprocating piston exerts an alternating pressure and suction on the lower piston. The lower or hammer piston is held from descending by pawl L, controlled by slide I, and by pawl Q controlled by lever H. In this situation every stroke of the upper piston lifts the hammer piston a little and the latter is held from descending by pawls L and Q, until it has reached 7 if the hammer is down it will be gradually raised to the top, or if it be stopped with the hammer down the first pressure on the pedal gradually raises it.

I am aware that pneumatic hammers controlled by lever and foot power have been made before, but

What I do claim and desire to secure by Letters Patent isr In a pneumatic hammer, a supporting frame, a cylinder supported by said frame, upper and lower pistons in said cylinder, the lower cylinder having a hammer rod, said hammer rod having a series of rounded corrugations and a series ofv ratchet teeth at its lower end, a reciprocating valve and stem, a pair of spring pressed pawls, one of said pawls normally engaging said rounded corrugations and the other engaging said beveled ends, engaging said valve stem at its upper end and engaging at its lower loosely mounted in said slot, a second arm end the pawl which engages said ratchet pivoted to said slide, and means for reciproteeth, a lever engaging at its upper end eating said arms.

with said valve stem and at its lower end GRIFFITH D. ROBERTS.

being connected to the pawl engaging said I lVitnesses:

rounded corrugations, a lever having a GEORGE E. BUNSA,

slanting slot, an arm having one end HARVEY ROWELL.

Copies of this patent may be "nbtainefl fei- 'fiire cents each, by addressing 'the Commissioner of Patents, Washington, D. C. 

